They shoot good from my 1/66 twist PA Hunter if I paper patch them up for a snug fit. Paper patching helps fill the deeper grooves of the patched round ball barrel and keeps it on the charge too. Don't know how they would do in the 1/48 twist but my bets are they would shoot good.
They shoot very nice in a 1/48...my only gripe is that they seem to foul the barrel very quickly when compared to round balls.
I could shot about 3 pa conicals and then the barrel needed to be wiped so I didn't have to hammer the ram rod down the barrel.
I shoot 'em and like 'em a whole bunch more than PRB. I've found that puttin a T\C bore button in between the powder and the conical cut's down on the barrel fouling and helps the gun shoot tighter groups when I shoot a 5 shot group and NOT clean or run an alcohol patch down the bore during this 5 shot set.